Centrifugal pump



w. H. CHURCH CENTRIFUGAL PUMP Jan. 15, 1935.

Filed March 21, 1930 4 Sheets-Sheet 1 JNVENTOR.

I i/El 'amzflllhwuch %Z Q ZQQ H15 ATTORNEY Jan. 15, 1935. w. H. CHURCH1,988,163

' I CENTRIFUGAL. P-UMP Filed March 21, 1930 i 4 Sheets-Sheet 2 El 2- j6'8 5 v INVENTOR. 1111' 1017 0111mm BY Z4 F H15 ATTORNEY Jan. 15, 1935.w, CHURCH 1,988,163

' CENTRIFUGAL PUMP Filed March 21, 1950 4 Shets-Sheet 3 11 INVENTOR.

mu amllllzumfi I? 4 BY H75 A TTORNE).

Jan. 15, 1935. w. H. CHURCH 1,988,163

CENTRIFUGAL PUMP Filed March 21, 1930 4 Sheets-Sheet 4 m; a 1', wi e n.-Z BY HIS ATTORNEY.

Patented Jan. 15, 1935 UNITED STATES PATENT OFFICE CENTRIFUGAL PUMPWilliam H. Church, Mount Vernon, N. Y., assignor to Ingersoll-RandCompany, Jersey City, N. 1., a corporation of New Jersey v ApplicationMarch 21, 1930, Serial No. 437,767

4Claims.

excess power usually employed to drive a centrifugal pump; Other objectsand advantages will be in part obvious and in part pointed outhereinafter.

As heretofore constructed, a centrifugal pump is primarily a constantpressure, variable volume machine when driven at constant speed. Whenmotor drive. has been considered in large pumps alternating current hasusually been used in connection with a constant speed induction orsynchronous motor. A serious problem occurs when under certainconditions variable pressure is required from such a pump. The pump hasusually been designed for the maximum pressure and all pressures belowmaximum were obtained by throttling, at a large sacrifice in power, thatis, the friction loss due to throttling represents power. waste. Theinvention described hereinafter overcomes this condition and allowsvariable pressure to be obtained without throttling and any.

great sacrifice in power.

The invention also allows' variable volume to be obtained at apredetermined pressure equal to or less than rated maximum pressurewithout throttling or any great sacrifice in power; due to the naturaldrooping characteristic of a centrifugal pump, as regards higherpressure at volumes less than maximum.

g In the preferred embodiment of the invention described in more detailhereinaftenthis is accomplished as follows:

The fluid passing through the centrifugal pump flows through a fluidturbine connected to the main shaft. This turbine develops the powerwhich has heretofore been lost in throttling and returns this power tothe main shaft, thereby removing part of the load from the motor whichdrives the pump. The net load on the motor is the difference between theload required by the pump and that developed by the turbine. The turbinemay be located in any suitable position with regard to the variousstages of a pump, either before the first stage, after the last stage orbetween stages as will be understood. I

By means of this construction the pump can be operated advantageously atpart loads because the possible recovery in power obtained through theinstrumentality of the turbine is increased as the load on the pump isreduced. At full load the turbine is of no effect and maximum power isexpended; but as the load diminishes, the 5 turbine is so operated thatmore and more power is recovered, and economical operation is thusfacilitated from full load down to part loads that are very small incomparison with the maximum load of, the pump.

The invention may be more completely understood by reference to thedrawings in which similar reference characters refer to similar partsand in which U Figure 1 is aside elevation of a blower driven 1 by aconstant speed electric motor,

Figure 2 is a vertical longitudinal section through part of the intakeportion of the blower.

Figure 3 is a section through the blower taken along the lines 3-3 ofFigure 2 looking into the 20 direction of the arrows, I Figure 4 is asection through the first stage of the motor taken along the line 4-4 ofFigure 2 looking in the direction of the arrows,

Figure 5 is a graph showing the comparative 2 characteristics ofpressures, volumes and power consumed of the blower. operating atconstant pressure with and without the turbine,

discharge D is adapted to be" driven by a substantially constant speedmotor or other drivins element E. In this instance the shaft F of theblower Bis coupled to the shaft G of the motor by any well known form ofcoupling, as for instance the flanged coupling H. The shaft F isprovided with suitable bearings 10 and extends into the blower B througha suitable bushing 11 held in place by a flanged ring 12 .bolted to abearing support member 13. On the shaft F are mounted a series of pumpimpellers 14 only one of which is shown, it being understood that theinvention is applicable to a pump having a single impeller orany number.

It is to be understood that a compressor of this type is adapted toproduce substantially a 55 r constant ratio of compression for any givenspeed of rotation of the shaft F and discharge volume. Therefore at a,constant discharge volume and constant speed a way of altering thedischarge pressure would be to vary the suction pressure accordingly.This has been done heretofore by throttling the inlet which throttlingrepresents a loss of pressure and consequently a waste of power.

In accordance with the practice ofthis invention a drop in pressure isproduced at the suction of the first stage impeller 14 by means of aturbine which comprises a rotor of vanewheel 15 having turbine blades'orvanes 16 and suitable relatively stationary entrance vanes '17 throughwhich the air entering at the inlet C is adapted to pass due to thesuction of the rotor 14. As is indicated in Figures 3 and 4 the turbineblades 16 are directed oppositely'to the blower vanes 117 of the rotor14. Preferably the turbine 'vanes 16 are suitably attached to shrouds18, in this instance beingshown made of steel bent at the ends over pins19 and flanged as at 20 to be attached to the shrouds.

As is well known the power of the turbine is partly due to the angle atwhich the actuating fluid is directed at the rotating vanes. Accordinglythe entrance vanes 17 are adjustable so as to vary the angle ofinclination of the fluid passing therethrough and directed at the vanes16.

To this end each vane 17 is mounted on a rotatable shaft 22' withsuitable bearings or bushings 23 inthe support member 13 dovetailedintothe housing 24 of the compressor B. The shafts 22 are adapted to berotated in unison by means of pin 25 extending laterally from a flange26 on each shaft 22. Pins 25 engage slots 27 in the periphery'of aring28 adapted to slide rotatively in the support member 13 being guidedtherein by a shoulder 29. Sliding of the ring 28 is effected by means ofa crank 30 on the shaft 31 mounted in the support member 13 and providedwith an external crank 32. The crank pin 30 fits into a slot 33 in thering 28 and may be provided with a suitable wear bushing 34 held inplace on the pin 30 by means of a washer 35 and screw 36. The entrancevanes 17 are suitably shrouded by side plates 38 and 39, the latterbeing supported by a general radially'extending web 40 of the casing 24.v

vIn order that the vanes 17 may be prevented from having end play orlooseness the shafts 22 are provided at their ends with spring members41 held in compression under washers 42 fastened in place by suitablytapered pins 43.

Leakage is prevented between the periphery of the turbine rotor 15 andthe side clearanceof the rotor 14.by means of a labyrinth packing andwearing ring 45 dovetailed into a ring 46 held in place on the web 40 bymeans of the side plate 39 and a ring 47.

- "Figures 5,. 6 and 7 are curves plotted from performance' of a gasblower constructed in accordance with the practice of this invention.Figure ,5 shows the performance -of the pump operating at constant speedand the discharge pressure maintained constant as indicatedsby the linebl Curvec shows the pressures corresponding to the discharge volumeswhen the turbine blades 16 and vanes 17 were removed. The saving inpower consumed is indicated by the shaded section between curves dand'f. Curve dshows the power consumption at constant pressure witha-i-portion of'the power being recovered or saved by theturbine..Curve.l shows the power consumption with a valve (not shown) throttlingthe intake and indicates nearly as great power as without throttling andthe turbine removed, the results of which are shown by curve e. Animportant advantage of the use of the turbine is the increased rangepossible with its use. 0rdinarily a blower or centrifugal pump isunstable at. low discharge volumes. a For instance, the pump beingtested could not be operated at vol- 'umes below those indicated by thecurve 9 because of surging. With .the turbine in operation this surgingand unstabiiity does not occur except at extremely low dischargevolumes.

In operation, assuming that the motor E is of a type which operates at asubstantially constant speed such as an induction or a synchronous type,there will be a fixed ratio of compression produced by the pump. By thisis meant that the ratio of the final pressure at the discharge D to thepressure at the entrance to the rotor 14 will be substantially aconstant. Certain losses due to friction will vary disproportionately.Heretofore, a common method of obtaining the desired discharge pressurewas to throttle the inlet by means of a suitable valve which could beadjusted to produce a suction pressure which in turn would produce thedesired discharge pressure. In such an arrangement the reduction insuction pressure was due to a friction loss in the valve and representsa waste of power. No such waste is found in the present invention sincethe fluid being pumped passes from the inlet C through the turbinecomprising the en-' trance vanes 17 and rotor 15 which are adjusted soas to develop power and correspondingly cause a pressure drop. Theamount of drop in pressure and power developed by the turbine may beadjusted by suitable manipulation of the lever 32 by which means theinclination of vanes 17, to the blades 16 is altered.

In Figure 6 is shown the performance of the pump operating at constantspeed, the pressure varying with the capacity. Curve b indicates therise in pressure with increase in volume and 0 shows the falling inpressure with the .turbine removed. The power consumption of the pumpwith the turbine is shown by d, that of the pump with turbine-removed bye, and the power used by the pump when throttled to give the samepressure and volume results shown by b are indicated by I.

Figure 7 shows horsepower curves for the pump operating at constantspeed and constant volume. The curves are plotted with power asordinates and percent of mean eflfective pressure as abscissa. Curve hshows the theoretical horse power and 7' shows the power with theturbine removed from the pump. Curve It shows the power consumption withthe turbine in operation. The saving in power is indicated by the Ineach case as shown by Figures 5, 6 and there is a very slight loss inefliciency at high volumes when the turbine is practically out ofoperation due to friction loss through the vanes 17 and blades 16. Thishowever is much more than offset by the very great increase in emciencyat partial loads.

The vanes 17 will in practice be adjusted'so that, when the pump' isoperating at full load they will be in radial position and the fluidentering the pump will flow directly toward the axis of-the shaft as itissues from the spaces bepower will be recovered by the turbine. Butwhen the pump is to be operated at part load, the vanes 17 will beshifted more and more away from the radial position so that more andmore power' will be given back by the turbine to the pump shaft. Theturbine thus compensates for the resistance to the inflow which thevanes 1'7 ofier. Hence, none of the losses usually encountered when apump of this type is operating at part load by throttling the fluid willbe sustained. In other words, the general arrangement is such as todiminish the power for driving the pump only when it is operating belowits rated outlet pressure or below its rated volume when the speed isconstant. At full rated pressure or volume the turbine does not act as amotor and no power is recovered and restored to the shaft; because asabove stated, the inlet guide vanes 17 at this time do not permit thefluid issuing from between them to have a tangential velocity componentin the direction of rotation. But when the load is reduced and the vanes17 are properly shifted, the inlet pressure drops and the outlet orcompression pressure falls also. The turbine thus operates at certaintimes with equal pressures at the inner and outer ends of the vanes 17,and no drop in pressure takes place through the turbine; and at othertimes with a very considerable pressure drop through the turbine. It isthus radically difierent in operation from the ordinary turbine andgives a different result.

The turbine can also be placed at the outlet end of the pump housing,and substantially the same result can be had, but with less advantage. Iprefer to locate it on the inlet side of the retor because there thepressure of the fluid is less. and the liability of external leakage isthus reduced. Also with a blower of this type there is usually amplespace available on the inlet side of the housing to receive the rotatingmember of the turbine and the guide vanes. No increase in the length ofthe main shaft or material alteration in the size or shape of thehousing is necessary.

The inlet guide vanes 17 are described above as being in substantiallyradial position when the turbine has no effect due to the greatlyincreased flow area between said inlet guide vanes which reduces thevelocity of flow and provides virtually no tangential component torotate the turbine: vane wheel. But of course I do not wish to belimited to inlet guide vanes which must be radial when the turbine isneutral. I may obviously construct my invention so that the turbine willrecover no power at full load on the pump when the inlet guide vanes arein some other position than radial, depending upon the character andarrangement of these vanes and those carried by the rotor 15; so long asthe combined eifects of the tangential components at both inlet andoutlet of the turbine vane wheel produce no resultant tangentialcomponent to rotate the turbine vane wheel.

Thus by the above constructions are accomplished among others theobjects hereinbefore referred to.

I claim:

1. A centrifugal pump for a fluid medium comprising a rotor having pumpvanes, a turbine placed to receive fluid passing through the pump, saidturbine comprising a vane wheel which revolves with said rotor and inletguide vanes mounted to direct fluid to said vane wheel, and means foradjusting said guide vanes from neutral position at full load toeffective positions at part load.

2. A centrifugal pump for a fluid medium comprising a housing, a rotorhaving pump vanes, a turbine placed to receive fluid passing through thepump, said turbine comprising a vane wheel which revolves with saidrotor and inlet guide vanes to direct fluid to said vane wheel, andmeans for adjusting said guide vanes from neutral position at full loadto eflective positions at part load, said turbine being disposed withinthe housing of the pump on the inlet side thereof.

3. A centrifugal pump comprising a housing with a rotor therein, saidrotor having pump vanes, a turbine placed to receive fluid passing amounted to revolve with said rotor and inlet guide vanes mounted todirect fluid to said vane wheel, and means to adjust said guide vanesfrom neutral position at full load, rendering the turbine of no eifect,to an effective position at part load to enable the turbine to recoverpart of the power to operate the pump, said turbine being disposed atthe inlet end of said housing.

WILLIAM H. CHURCH.

